08/13/2015 Idaho DEQ Smoke Forecast

Updated 1100am MDT Thursday, August 13, 2015

Valid through: Noon MDT Friday, August 14, 2015

Smoke Outlook

Air quality is currently ranging from Moderate to Unhealthy across northern Idaho and in southwest Idaho east to Twin Falls and north to Garden Valley and McCall.  Air quality is forecast to remain in the Moderate to Unhealthy category for the 24hr standard across the northern Idaho.  Impacts are from regional fires burning in Washington State, California, Oregon, and a multitude of local fires that started this week in the Clearwater drainage.

Nez Perce Reservation:  24-hour monitor readings range from Moderate (Lapwai, Reubens) to Unhealthy (Orofino, Kamiah).  Hourly readings are fluctuating from Moderate to Hazardous, depending on location and wind direction.  The Nez Perce Tribe will continue their Air Quality Advisory.  Please contact the Nez Perce Tribe for more information: airquality@nezperce.org.

An upper level low pressure system off the Oregon Coast will continue to provide warm, moist air into all of Idaho this afternoon and tomorrow.  This will allow for a persistent chance of lightning and thunderstorms this afternoon and into tomorrow.  Surface winds will be light today and generally from the south-southwest today but due to the low speeds, local terrain will drive wind direction and limit horizontal movement.  Mixing heights are expected to be quite high (8,000-10,000 ft AGL) which should promote vertical mixing.  Tomorrow, a cold front will pass through in the afternoon and evening which will provide gusty winds at the time of the frontal passage.  Also likely will be continued dry thunderstorms in the afternoon.  A weather pattern change is expected to take place after this frontal passage and into the weekend with cooler temperatures across the state.  Some slight warming will occur Sunday and Monday as a flat ridge develops within a zonal flow pattern aloft.  Southern Idaho will also continue to experience impacts from the Soda Fire burning in the Owyhees.

The strongest smoke impacts are occurring across the Clearwater drainages and southwest Idaho.  This will continue into the afternoon and especially this evening as a nocturnal easterly flow develops within the Clearwater and a southerly drainage develops within the Purcell Trench.  Expect to experience impacts from the Canadian Border south to Coeur d’Alene and along the low spots to Lewiston and east essentially to within the Lochsa Drainage.  The highest impacts are expected to be within the drainages into Camas and Weippe Prairies, as well as down to the Lewiston-Clarkston Valley.  In southern Idaho, impacts will be greatest within the Treasure Valley, from Boise, west into Oregon, and north to McCall and Garden Valley.  Nocturnal drainage flow and low boundary layer heights will contribute to greater impacts in that area tonight.  Impacts are expected across the Treasure Valley and east tomorrow (as far east as Salmon) as a northwest flow pattern develops tomorrow afternoon across southern Idaho.

DEQ Air Quality Advisories:

Idaho DEQ has issued a Stage 1 Forecast and Caution for the following areas:

·                     Latah, Nez Perce, Lewis, Clearwater, Idaho Counties, river corridors and surrounding areas (off the Nez Perce Reservation) effective  through 10:00am PDT August 14, 2015, at which time is will be re-evaluated and either extended or lifted.

Smoke forecasts are dependent on predicted fire growth and weather.  If conditions change unexpectedly, impacts could occur.  When visibility starts to go below 5 miles, sensitive groups should minimize outdoor activities.  Everyone else should minimize prolonged or physical activity outdoors.  Refer to the Smoke and Health Tab on the Idaho Smoke Information Blog for additional health information. 

Your eyes are your best tools to determine if it’s safe to be outside.  Even if you smell smoke, the air quality may still be good. 

AQI Category	Visibility (miles)
Good	11+
Moderate	6-10
Unhealthy for Sensitive Groups	3-5
Unhealthy	1½  -2¾
Very Unhealthy	1-1¼
Hazardous	Less than 1

How to estimate air quality based on visibility for areas without an air quality monitor or airport visibility estimate:

a. Face away from the sun.

b. Determine the limit of your visible range by looking for targets at known distances (miles).

c. Visible range is when an object you can easily see in the distance disappears.

d. Use the visibility values above to determine the local wildfire smoke category.